rotor

noun

Aeronautics. a system of rotating airfoils, as the horizontal ones of a helicopter or of the compressor of a jet engine.

any of a number of tall, cylindrical devices mounted on a special ship (rotor ship) and rotated in such a way that the Magnus effect of wind impinging on the cylinders is used to drive and maneuver the vessel.

(in a self-winding watch) a weight eccentrically mounted on an arbor for keeping the mainspring wound.